Method and apparatus for inserting digital media advertisements into statistical multiplexed streams

ABSTRACT

A method and system for the insertion of local signals, including digital media advertisements, into statistically multiplexed streams is presented. The rate control and timing information is computed and is used to specify the insertion time and rate parameters for digital advertisements. In one embodiment, a maximum bit rate over the advertisement duration is specified. The maximum bit rate may be constant or may vary in time, such that high bit rate portions of the advertisement are supported. High bit rate portions of the advertisements in different program streams may be staggered, such that the total bandwidth required does not exceed a maximum, but allowing for high bit rate portions of advertisements. Custom bit rate profiles for advertisements may also be defined, with the profiles being defined at a high granularity or a low granularity.

This application claims priority under 35 U.S.C. §119(e) for provisionalapplication No. 60/160,549 filed on Oct. 20, 1999.

BACKGROUND OF THE INVENTION

The transition to digital video allows video programming to betransmitted in a digital format through satellite systems, cablesystems, and over the air broadcast systems. Digital compression, and inparticular, the Motion Pictures Expert Group (MPEG) Standard allows formultiple digital programs to be carried in a section of spectrum whichpreviously could only carry one analog program. Typically, the 6 MHzwide channel which carried one analog program can carry six to tendigitally encoded and compressed programs.

As part of the digital transmission process, multiple programs arestatistically multiplexed such that the bit rate requirements for eachprogram are met and when programs do not have a high bit raterequirement, other programs can use the available bandwidth. As anexample, when a football game is statistically multiplexed with a talkshow, the football game will be allocated sufficient bandwidth to permitaccurate representation of the play on the field and the motion of theplayers. The talk show program will be allocated a minimum amount ofbandwidth such that the people appearing on the program can be seenclearly. However, in an instance when there is motion in the talk showprogram as may be the case when the participants on the talk show beginto hurl chairs at one another, the multiplexing process will allocateadditional bandwidth to the talk show and in the event that there is aminimum bandwidth requirement in the football game, that bandwidth willbe allocated from the football game to the talk show. Clearly, whenthere are multiple programs, bandwidth can be allocated among all theprograms such that the motion can be accurately represented in eachprogram and the overall statistically multiplexed stream optimized.

Several problems arise in statistically multiplexed programs includingthe difficulty in separating programs and substituting provisionalprogramming. As an example, at a re-transmission point such as a cabletelevision local head end it becomes difficult to remove one programfrom the statistically multiplexed stream and insert another program.This difficulty arises from the fact that the bandwidth of the programis varying constantly according to the bandwidth tradeoffs achieved bythe statistical multiplexing equipment at the origin point.

Another difficulty is the insertion of advertisements into thestatistically multiplexed streams. Because the bandwidth of each programis varying, an original advertisement inserted into the program streamat the origin point will have a time varying bandwidth. Insertinganother advertisement at the re-transmission point is not readilyfacilitated in existing systems and equipment because the bandwidth isvarying and in some cases not easily discernible by the equipment at there-transmission point. Because local advertisement insertion is animportant part of many broadcast services and generates significantrevenue, it is necessary to be able to remove the initialadvertisements, which are part of the program stream and substitute newadvertisements.

U.S. Pat. No. 5,715,018 entitled “Digital Advertisement Insertionsystem” issued on Feb. 3, 1998, provides means for digitizing,compressing and storing analog/audio video source information; anddecompressing the information to regenerate an analog signal. A methodbased on this patent includes receiving motion video information from ananalog source; digitizing, compressing and storing the received motionvideo information in a computer data file such that upon decompression,broadcast quality motion video information is obtained; selecting andediting at least a portion of the stored motion video information;decompressing the selected and edited portion of the stored motion videoinformation to obtain broadcast quality motion; and regenerating ananalog signal from the selected and edited portion of the stored motionvideo information; inserting the regenerated analog signal in place of abroadcast signal on a channel at a predetermined time; and providingsynchronization of the regenerated analog signal to the broadcastsignal.

An apparatus based on this patent includes means for inserting a signalrepresenting motion video information in place of a broadcast signal ona broadcast channel at a predetermined time, and wherein the broadcastchannel transmits the motion video information at a field per secondrate; means for providing synchronization of the signal representingmotion video information to the broadcast signal; a randomly-accessiblecomputer-readable medium for digitally storing in a data file compressedimage data for a sequence of digital still images, including an imagecorresponding to each field of the motion video information to betransmitted in the broadcast channel, such that upon decompression,broadcast quality motion video information is obtained; and a computerincluding means for editing the sequence of digital still images, meansfor accessing the sequence at the predetermined time, for decompressingthe sequence to obtain broadcast quality motion video information andfor generating the signal to be inserted into the broadcast channel fromthe accessed sequence.

U.S. Pat. No. 5,600,366 entitled “Methods and Apparatus for DigitalAdvertisement Insertion in Video Programming”, issued on Feb. 4, 1997permits timely and correct switchovers from network programming to localadvertising in ways which occur smoothly without disruption inperception to the viewer. Switchovers occur at packet or frameboundaries and are designed to occur upon detection of idle informationfrom a network source. An apparatus based on this patent includes meansfor receiving externally supplied programming comprising analog videoinformation and embedded tone cues including a pre-roll cue and a rollcue, detecting said tone cues and converting the analog videoinformation to digital video information; means for activating digitalvideo storage in response to one of said tone cues preparatory toinitiating playback; and means for initiating playback from said storagein response to detecting an idle condition from said digital videoinformation.

Another apparatus based on this patent includes means for receivingexternally supplied programming from a plurality of sources, each sourceproviding programming comprising analog video information and embeddedtone cues, and for converting the analog video information to digitalvideo information; storage means for storing a plurality of localprograms; common means for monitoring all of said sources to detect oneor more tone cues from a source and for preparing said storage means forplayback of respective one or more of said local programs to besubstituted for said externally supplied programming from a sourcesending at least one of said one or more tone cues; and means forinitiating playback from said storage means of respective one or more ofsaid local programs to be substituted for said externally suppliedprogramming from a source in response to detecting an idle conditionfrom said digital video information of said source.

A method based on this patent includes receiving externally suppliedprogramming comprising analog video information and embedded tone cuesincluding a pre-roll cue and a roll cue, detecting said tone cues andconverting the analog video information to digital video information;activating video storage in response to one of said tone cuespreparatory to initiating playback; and initiating playback from saidrecorder in response to detecting an idle condition from said digitalvideo information.

Another method based on this patent includes receiving local digitalvideo programming and providing it to a user; receiving externallysupplied analog video programming and embedded tone cues including areturn to network cue, detecting said return to network cue; convertingsaid analog video programming to digital video information upon receiptof said return to network cue; and terminating operation of videostorage in response to detection of an idle condition in said localdigital video programming.

U.S. Pat. No. 5,956,088 entitled “Method and Apparatus for ModifyingEncoded Digital Video for Improved Channel Utilization” issued on Sep.21, 1999 and U.S. Pat. No. 5,862,140 entitled “Method and Apparatus formultiplexing Video Programs for Improved Channel Utilization” issued onJan. 19, 1999 both provide a method (and apparatus) for increasingchannel utilization for a data channel transmitting a multiplex of a setof one or more encoded program streams. Each program stream in said setbeing decodable by a corresponding decoder. Each corresponding decoderincluding a corresponding decoder buffer, the decoder buffers having amaximum allowable size. The method comprising selecting encoded picturesto be modified, said selecting according to a criterion, which includespreventing any underflow of any decoder buffer, modifying each saidselected encoded picture to form a corresponding modified encodedpicture, said modified encoded picture having less data than saidselected encoded picture, and transmitting the corresponding modifiedencoded pictures through the channel in place of the selected encodedpictures. In one embodiment of these patents, modifying deletes eachselected encoded picture. In another embodiment of the patents, wherethe encoded program streams include predictively encoded pictures,selecting selects predictively encoded pictures that are not anchorpictures, and modifying deletes the prediction error data from each saidselected encoded picture.

In a further embodiment of these patents, one or more additional datachannels are used to send augmentation information. The augmentationinformation can be used by specially equipped receivers to correct theimpairments that would normally occur when decoding the modified signalreceived from the data channel. In yet another embodiment of the patent,augmentation information is sent using the same data channel that isused to transmit the modified pictures. In this case, the informationthat is removed by modifying is transmitted before it is needed fordecoding and at a time when the data channel is not fully utilized.Certain receivers equipped with sufficient storage can receive and storethe augmentation information until it is needed. Alternatively, if theadditional storage is used to insert additional delay between the timethat data is received and the time that data is decoded, then theaugmentation information can be sent after it would be needed by aconventional receiver.

A system of these patents comprise primary and overflow demodulatorsconfigured to demodulate data from the primary and overflow channels,respectively; a first demultiplexer, coupled to the primary demodulator,configured to extract a primary packet stream from an output of theprimary demodulator; a second demultiplexer, coupled to the overflowdemodulator, configured to extract an overflow packet stream from anoutput of the overflow demodulator; a buffer coupled to the seconddemultiplexer; a time stamp comparator, coupled to the firstdemultiplexer and the buffer, configured to compare a time stampassociated with a next packet from the primary packet stream with a timestamp associated with a next packet from the overflow packet stream; anda packet multiplexer, coupled to the first demultiplexer, the buffer andthe time stamp comparator, configured to select one of the next packetsfrom the primary packet stream and the overflow packet stream inresponse to a comparison made by the time stamp comparator.

U.S. Pat. No. 5,029,014 entitled “Ad Insertion System and Method forBroadcasting Spot Messages Out of Recorded Sequence”, issued on Jul. 2,1991, provides an advertisement insertion system and method transmitspot messages during intervals in a broadcast transmission and provideimmediate access to stored spot messages, in any sequential order, witha single video source. Custom spot messages can be created bysuperimposing graphics over selected video signals and simultaneouslytransmitting those signals with appropriate audio signals.

A system of this patent comprises a first playing means for playing spotmessages stored in a recorded sequence on a video source, and controlmeans for switching a broadcast system from program signals of ascheduled broadcast, selecting and causing said first playing means toplay into said broadcast system in immediate succession a plurality ofspot messages out of said recorded sequence without intervening materialfrom another playing means, and switching said broadcast system back toprogram signals of a scheduled broadcast.

A method of this patent comprises selecting video, audio and/or graphicsignals to form custom spot messages; accessing the selected videosignals on a laser disk; accessing selected audio signals which are tobe simultaneously broadcast with said accessed video signals; andswitching from broadcast transmission to spot message transmission toco-broadcast said accessed video and audio signals as said spot messageswith an audio component according to a programmed time schedule and outof a pre-recorded sequence of spot messages on said laser disk.

U.S. Pat. No. 5,966,120, entitled “Method and Apparatus for Combiningand Distributing Data with Pre-formatted Real-time Video”, issued onOct. 12, 1999, relates to providing constant bit rate distribution ofvariable bit rate-encoded video programs, along with Auxiliary Data of ageneral character, to one or more receivers. At a particular receiver, acustomized augmented video program is created by inserting selectedportions of the Auxiliary Data into a selected encoded video program.The encoded video portion of the augmented video program can betransmitted, decoded and displayed in real time, while the AuxiliaryData need not be transmitted in real time but can be stored locally atthe receiver for real-time presentation at a later time. Real timepresentation might include insertion into the video program while nonreal-time presentation might include insertion into non-videoapplications separate from the video program.

A method of this patent comprises the steps of receiving the primarydata stream; detecting fill data in the primary data stream; insertingan auxiliary data stream in place of the fill data; and adding locationdata for the programs and for the auxiliary data; to form a modifieddata stream for distribution to a plurality of receivers configured forindividually extracting selected portions of the modified data stream inaccordance with the location data.

Another method of this patent comprises the steps of statisticallymultiplexing a plurality of encoded video programs; monitoring thestatistically multiplexed encoded video programs for the occurrence of afill packet; maintaining a buffer of auxiliary data segments; replacingthe fill packet with at least one segment of the auxiliary data streamfrom the buffer if the segment is smaller than the size of the fillpacket; adding location data for the encoded video programs and for theauxiliary data; to form a modified data stream for distribution to aplurality of receivers configured for individually extracting selectedportions of the modified data stream in accordance with the locationdata.

A system of this patent comprises a program multiplexer forstatistically multiplexing a plurality of encoded video programs to themodified data stream; a data insertion controller coupled to receive amultiplexed program stream from the program multiplexer and forinserting auxiliary data therein to yield a modified data stream; and aprogram map insertion controller coupled to receive the modified datastream for adding location data for the encoded video programs and forthe auxiliary data to the modified data stream. Another system comprisesa multiplexer for statistically multiplexing a plurality of encodedvideo programs; a first controller for adding auxiliary data to theoutput of the multiplexer; a second controller for adding location datafor the encoded video programs and for the auxiliary data to the outputof the first controller, thereby forming a modified data stream; adistribution channel for distributing the modified data stream to atleast one receiver; a processor for determining location data from thedistributed modified data stream; a first demultiplexer for selecting anencoded video program from the modified data stream in accordance with afirst predetermined characteristic of the processor and the locationdata; a second demultiplexer for selecting local auxiliary data from themodified data stream in accordance with a second predeterminedcharacteristic of the processor and the location data; a storage devicefor storing the local auxiliary data from the second demultiplexer; andan augmentation unit for associating the encoded video program and thestored local auxiliary data to form a receiver-specific augmented videoprogram for decoding and display.

SUMMARY OF THE INVENTION

The present invention provides a system and method for computing rateprofiles associated with the multiplexed program streams. The rateprofiles may be used for inserting local advertisements and allowingsubstitution of original advertisements or other programming withinserted advertisements. In one embodiment, a predetermined bit rateprofile is specified for the compression of an advertisement with thespecification extending from the start point of the advertisement to theend point. The digital media advertisement is compressed according tothe specified profile and inserted into the advertising opportunity.

The predetermined bit profile may comprise a maximum bit rate, a maximumbit rate and a minimum bit rate, a minimum or maximum number of bitsover the avail or a subset or portion of the avail, or a time varyingprofile defined from the start point to the end point. The profile maybe modeled as a piece-wise linear model, allowing bandwidth to change atspecified moments during the advertisement.

The specified predetermined bit rate profile may comprise only a minimumbit rate and null packets may be inserted to make up the differencebetween the minimum bit rate and the actual bit rate which occurs in thestatistically multiplexed stream.

In a statistically multiplexed stream where there are multiple programswith varying bit rates for each program, multiple bit rate profiles maybe defined such that each advertising opportunity has a specific bitrate profile defined for it. The individual rate profiles may be definedsuch that the sum of all the profiles is equal to the maximum allowedbit rate in the statistically multiplexed stream during theadvertisement. The predetermined bit rate profile for the stream mayspecify the instantaneous sum of the first bit rate profile and thesecond bit rate profile or may simply define the total number of bitsfrom the start point to the end point of the first bit rate profilesummed with the second bit rate profile.

In inserting advertisements in various multiplexed program streams, itis possible to create the bit rate profiles for the individualadvertisements such that they are complementary. That is, the highbandwidth portions of the first bit rate profile correspond to the lowbandwidth portions of the second bit rate profile. This method can beextended across multiple profiles such that high bandwidth portions ofan advertisement correspond with at least one low bandwidth portion inanother program stream, thus allowing for multiple simultaneous highbandwidth portions of advertisements. Alternatively, high bandwidthportions of advertisements may be staggered in a predetermined mannersuch that ads are allowed to have sections of high motion or other highbandwidth requirements but that these portions do not occursimultaneously.

These and other features and objects of the invention will be more fullyunderstood from the following detailed description of the preferredembodiments, which should be read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part ofthe specification, illustrate the embodiments of the present inventionand, together with the description serve to explain the principles ofthe invention.

In the drawings:

FIG. 1 is a block diagram illustrating an exemplary processingassociated with the generation of statistically multiplexed streams;

FIGS. 2A and 2B illustrate the time varying bit rates for an incomingprogram stream and an outgoing stream with inserts respectively;

FIGS. 3A and 3B illustrate the time varying bit rates for twostatistically multiplexed streams having complementary advertisementavails;

FIGS. 4A–4C illustrate staggered avail profiles for three simultaneousmultiplexed streams;

FIG. 5 illustrates two profiles having coarse granularity and finegranularity respectively; and

FIG. 6 illustrates monitoring of the total number of bits during theavails.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In describing a preferred embodiment of the invention illustrated in thedrawings, specific terminology will be used for the sake of clarity.However, the invention is not intended to be limited to the specificterms so selected, and it is to be understood that each specific termincludes all technical equivalents which operate in a similar manner toaccomplish a similar purpose.

With reference to the drawings, in general, and FIGS. 1 through 6 inparticular, the system and method of the present invention is disclosed.

FIG. 1 illustrates an exemplary processing associated with thegeneration of statistically multiplexed program streams. As illustrated,each video encoder 110 produces a video programming stream 117 which isreceived by the statmux 130. The statmux 130 includes a rate controlunit 120, which provides a rate control signal 115 to each video encoder110. This rate control signal 115 is used by the video encoder 110 tocompress the programming according to the requirements of the statmux130. The statmux 130 acts to control the total bandwidth utilized by themultiple video encoders 110. The actual number of video encoders will bedetermined by the amount of bandwidth available to the statisticalmultiplexer 130.

The origin point 100 for the video may be a studio location, a satelliteuplink location, a cable centralized transmission point, in-home server,or other video origin point.

Once the statmux 130 creates a statistical multiplexed stream 135, it istransmitted to the re-transmission point 155. Rate control informationmay be transmitted as part of the statistically multiplexed stream 135through use of an inserted rate control signal 140 which is combinedwith the programming. Alternatively, the rate control information may betransmitted as a separate rate control signal 150 that may be reinsertedthrough use of a rate control reinsertion signal 145. In anotherembodiment, rate control information may be transmitted only as MPEGvideo rate parameters.

The re-transmission point 155 may comprise a cable television head end,a satellite downlink receiver, or can even be home equipment such as atelevision set top, personal computer, or other equipment, whichreceives the statistically multiplexed stream 135.

At the re-transmission point 155, a program inserter 160 works inconjunction with an insertion server 165 to reform the program streamswith substituted advertisements. This new program stream comprises theoutgoing program stream multiplex 170. The outgoing program streammultiplex 170 is received by a decoding point 175 that includes aprogram decoder 180, which decodes the digital video stream and presentsit to a display unit 190. In one embodiment, the program decodercomprises an MPEG decoder and is coupled to a television which acts asdisplay 190. In another embodiment, the program decoder 180 comprisesanother type of digital video decompression system and is coupled to apersonal computer or other display device.

From a business perspective, the fact that advertisements have beeninserted into what are termed “ad avails” creates difficulty at there-transmission point 155 because the advertisement may not be suitablefor the viewers in that geographic area, the service provider may beable to receive more revenue by substituting the original advertisementwith a new advertisement. As an example, it may be desirable for a cableoperator to replace a nationally broadcast advertisement with a localadvertisement for a restaurant, car dealership, or other locallyprovided service. If the cable operator had permission to substitute theads, they will want to remove the original advertisement from theprogramming stream and substitute the local advertisement. The term “adavail” refers to any available spot for advertising which may be filledwith an original advertisement or a blank spot in the programming.Alternatively, it may be possible to interrupt the program stream andinsert an advertisement where there was no original advertisement. Inthis case, the “ad avail” becomes created although it did not originallyexist.

The rate control signal 115 may contain rate control information as wellas insertion timing information to enable program and advertisementinsertion at re-transmission points 155. The information which may beincluded consists of the minimum or actual rate during the avails asdetermined by predefined rate profiles, or the actual rate profile ofthe upcoming avail in predefined or specified time units. The ratecontrol signal 115 may indicate a fixed minimum rate which may bedifferent during each ad avail and/or the total number of bits, bites,packets, or other measurable units in the ad avail.

The separate rate control signal 150 as illustrated in FIG. 1 serves asa means of delivery for rate information and can include prearrangementby any means including e-mail, written or verbal specifications, ortemplates designated by a standards body, or an actual out-of-band orout-of-multiplex transmission which represents the specific rate controlinformation.

FIG. 2A illustrates time varying bits associated with an incomingprogram stream. Incoming program rate 205 is drawn on Y axis and time207 is drawn on X axis. The illustration of the incoming program rate205 as compared to function of the time 207, illustrates that a definedminimum 230 over a pre-determined period of time may be determined. Thepredetermined time period may have an associated avail start 210, availend 220, and an example rate 240. Thus, the incoming program stream hasa bit rate which varies and exceeds the defined minimum 230 for theavail having avail start 210 and avail end 220. Thus, the underlinedprogram may actually utilize more bandwidth than the avail, but theavail will be assigned the minimum defined bandwidth 230.

FIG. 2B illustrates the time varying bit rates for an outgoing stream.FIG. 2B further illustrates an avail committed information rate (CIR)260 which is the minimum bit rate that will be guaranteed for use forthe insertion of the advertisement in the avail. As shown in FIG. 2B,one or more null packets 250 can be inserted to make up the differencebetween the CIR 260 and the actual bit rate as defined by the examplestream 240.

For exemplary purposes, FIGS. 3A and 3B illustrate exemplarystatistically multiplexed streams having predefined avail rate profiles.FIG. 3A represents a first stream in a multiplex, and FIG. 3B representsa second and simultaneous stream in the same multiplex. As illustratedin FIGS. 3A and 3B, a number of avail profiles are specified includingavail profile #1 (310); avail profile #2 (320); avail profile #3 (330);avail profile #4 (340); avail profile #5 (350); avail profile #6 (360);avail profile #7 (370); and avail profile #8 (380). As illustrated,avail profile #1 (310) may be complementary to avail profile #5 (350) inthat these avail profiles occur simultaneously in the multiplexedstream. This may be the case when the advertisements are synchronoussuch that the start times are equal or nearly equal and the end timesare equal or nearly equal. In such a case it is possible to define theavail profiles such that they complement each other to allow for adefined rate for multiple simultaneous profiles in a single multiplexwherein high bandwidth requirements are permitted at a time in availprofile #1 (310) which is complementary to the high bandwidthrequirement time in avail profile #5 (350).

FIGS. 4A–4C represent avails in three program streams in a multiplexedsignal. As shown, several avails are defined including avail 1A 410,avail 2A 420, avail 1B 430, avail 2B 440, avail 1C 450 and avail 2C 460.The profiles for these avails are defined such that the high bandwidthtimes are staggered.

FIG. 5 illustrates custom profiles including avail 1A 510 and avail 2A520 with profiles defined such that avail 1A has a coarse custom profilewith the bit rate varying over time substantially. Avail 2A 520 has afine time granularity for definition of the rate such that the definedbit rate may vary dramatically over a period as short as a second orseveral milliseconds. This method allows for the bandwidth in thestatistically multiplexed stream to be utilized optimally such that whenthe initial advertisement is removed the inserted advertisement has abit rate which matches that of the original advertisement closely.

FIG. 6 illustrates monitoring of avail 1A 610 and avail 2A 620 such thatthe total number of bits, packets, or other digital measurement iscalculated. This can be visualized as the area under the rate curve. Byspecifying the total number of bits, short avails can be defined andstreams can be defined for decoders with large buffers.

It is to be noted that a typical MPEG buffer has a latency of less than1 second. Thus, the sections of video must be delivered and used withinthat time. However, the decoders with larger buffers, as may be includedin equipment with large amounts of memory, such as set top devices, maydefine a 30 second latency and allow bits to be delivered at any time inthe 30 second window. Such large buffers can provide additionalflexibility in advertisement insertion. One way in which a large buffercan be used is by using the memory to buffer the video stream of theavail, allowing low bit rate delivery of high bit rate ads, andinserting the ads at the appropriate moment. Thus, although thestatistically multiplexed video stream may not be capable oftransporting a high bit rate advertisement for real time display, thesystem may receive the advertisement over a period of several secondsand subsequently display the high bit rate advertisement.

The extensions of the techniques disclosed herein can be utilized andinclude concepts such as profiling of avails which includes profiling ofportions of the pre-advertisement and post-advertisement content. Forexample, by profiling the start/end of television shows it becomespossible to allow higher bit rate and/or higher quality advertisements,based on the occurrence of low bit rate segments of televisionprogramming in adjacent channels. When the start/end of programming inan adjacent channel results in a low bit rate and the avail overlapsthis start/end segment, the bandwidth from the programming can be usedfor the avail. For example, ads on channel 2 can benefit from rollingcredits on channel 3 at the end of the show on channel 3 when the endtime of the programs on channels 2 and 3 are staggered, as frequentlyoccurs.

Another technique which can be utilized as part of the present inventionis blind profiling, in which no external rate information other than theMPEG rate values in the video stream is transmitted to the insertionpoint, which in one embodiment, is the statistical multiplexer 130. Atthe insertion point, the insertion device optimizes use of the availbits, and profiles are created based on the ads which originate fromoff-line encoders, with the statistical multiplexing process allowingoptimal use of bits for the highest quality and full control over theimages. The resulting profiles can be transmitted in the inserted ratecontrol signal 140 or through use of the separate rate control signal150.

In the blind profiling technique, the secondary insertion point 155,which in one embodiment is the retransmission point, utilizes theprofiles of the original ads as the basis for compressing orre-compressing replacement ads, which will be forced to match theprofiles of the original ads. One advantage of this technique is that itallows for the coexistence of both profiled and unconstrained ads inwhich the statistical multiplexer 130 accommodates the advertisement inits original form, using traditional statistical multiplexing techniquesfor compression. The profiles created by the first instance ofcompression can be piecewise linear profiles with the linear segmentsextending periods of one second or longer, minimum or maximum bit rateprofiles, high granularity profiles which track the bandwidth allocatedto the avail in increments ranging from a few milliseconds to one secondor more, or total bit rate profiles.

Another advantage of blind profiling is that at the initial insertionpoint, the profile of the avail is only constrained by the statisticalmultiplexing process and not by a predetermined profile. Using thistechnique, it is possible for content providers to sell avails andinsert the advertiser's material while insuring a high qualityadvertisement. The local broadcaster, using the profile generated by theinitial insertion, can substitute the original advertisement withanother advertisement which matches the profile. The substitutedadvertisement may have a profile which approximates that of the originaladvertisement, or may be compressed or re-compressed to match orapproximate the profile of the original advertisement.

Although this invention has been illustrated by reference to specificembodiments, it will be apparent to those skilled in the art thatvarious changes and modifications may be made which clearly fall withinthe scope of the invention. The invention is intended to be protectedbroadly within the spirit and scope of the appended claims.

1. A method for inserting advertisements into a statisticallymultiplexed transmission stream containing a plurality of programstreams with a plurality of advertising opportunities, the methodcomprising: determining a first avail rate profile for a first availwithin a first program stream, wherein the first avail rate profile isbased at least in part on a first program stream rate profile for thefirst program stream; determining a second avail rate profile for asecond avail within a second program stream, wherein the second availrate profile is based at least in part on a second program stream rateprofile for the second program stream; generating a composite avail rateprofile based on the first avail rate profile and the second avail rateprofile; assigning a first advertisement rate profile to the first availand a second advertisement rate profile to the second avail, wherein thefirst advertisement rate profile is not limited by the first avail rateprofile and the second advertisement rate profile is not limited by thesecond avail rate profile, and wherein a combined first advertisementand second advertisement rate profile is limited by the composite availrate profile; compressing the first advertisement according to the firstadvertisement rate profile and the second advertisement according to thesecond advertisement rate profile; and inserting the compressed firstadvertisement in the first avail and the second advertisement in thesecond avail.
 2. The method of claim 1, wherein the composite avail rateprofile specifies the instantaneous sum of the first avail rate profileand the second avail rate profile.
 3. The method of claim 1, wherein thefirst advertisement rate profile is complementary with the secondadvertisement rate profile.
 4. The method of claim 1, wherein the firstadvertisement rate profile has a first high advertisement rate portion,the second bit rate profile has a second high bit rate portion, and thefirst high bit rate portion and the second high bit rate portion arestaggered.
 5. A system for inserting advertisements into a statisticallymultiplexed transmission stream containing a plurality of programstreams with a plurality of advertising opportunities, the systemcomprising: a statistical multiplexer capable of determining a firstavail rate profile for a first avail within a first program stream and asecond avail rate profile for a second avail within a second programstream; a video compressor capable of compressing a first advertisementand a second advertisement at an aggregate rate profile which is lessthan or equal to sum of the first avail rate profile and the secondavail rate profile; and a video inserter capable of inserting thecompressed first advertisement in the first avail and the secondcompressed advertisement in the second avail.
 6. The system of claim 5,wherein said video compressor compresses the first advertisement at thefirst avail rate profile and the second advertisement at the secondavail rate profile that is complementary with the first avail rateprofile.